1. Field of the Invention
The present invention relates to an electrical connector assembly for electrically connecting an electronic package such as a central processing unit (CPU) with a circuit substrate such as a printed circuit board (PCB), and particularly to a land grid array connector assembly having a fastening device for securely and reliably locating the CPU therein.
2. Description of Prior Art
An integrated circuit (IC) package having leads arranged in a land grid array (LGA) is known as an LGA package. LGA packages have relatively low height, which saves valuable space in electronic assemblies.
Connectors for removably mounting an LGA package on a PCB are known as LGA sockets. An LGA socket combined with ball grid array (BGA) technology typically comprises a thin and substantially flat insulative housing which is positioned between the LGA package and the PCB. The housing defines an array of passageways receiving electrical contacts therein. The contacts correspond with the array of leads of the LGA package. Each contact has a pair of opposite free ends that project beyond opposite top and bottom external surfaces of the housing. Prior to mounting of the LGA package on the PCB, the free ends are spaced apart a predetermined distance. The free ends are respectively engaged with corresponding contact pads on a bottom surface of the LGA package, and soldered to contact pads on a mounting surface of the PCB.
This kind of conventional LGA socket is detailed in xe2x80x9cNonlinear Analysis Helps Design LGA Connectorsxe2x80x9d (February 2001, Connector Specifier Journal). Similar kinds of LGA connectors are also disclosed in U.S. Pat. Nos. 5,192,213, 5,199,889, 5,232,372, 5,320,559 and 5,362,241.
FIGS. 9 and 10 show a conventional land grid array connector assembly 6 comprising a fastening device 60, and a socket 61 received in the fastening device 60. The fastening device 60 comprises a generally rectangular frame 63, and a lever 62 and a metal clip 64 respectively mounted to opposite sides of the frame 63. The frame 63 defines a pair of locating slots 66 at one side thereof, and a pair of guiding grooves 65 at an opposite side thereof. Each guiding groove 65 is bounded by a first wall 651 and an opposite second wall 652. The lever 62 comprises a pair of locating portions 623 pivotally received in the locating slots 66 of the frame 63, a driving portion 621 disposed between and offset from the locating portions 623, and a handle portion 622 bent perpendicularly from a distal end of one of the locating portions 623. The clip 64 comprises a pair of acting portions 641 movably received in the guiding grooves 65 of the frame 63, and a driving hook 644 formed at a free end thereof.
In use, the clip 64 is firstly rotated to be perpendicular to the frame 63, with the acting portions 641 disposed in the guiding grooves 65 close to the first walls 651. The handle portion 622 of the lever 62 is horizontal, and the driving portion 621 is at a highest position. A central processing unit (CPU) 7 is attached on the socket 61, and a copper plate 8 which functions as a heat dissipation device is attached on the CPU 7. The clip 64 is rotated down to a horizontal position, with a pair of pressing arms 643 and a pair of pressing pads 645 of the clip 64 abutting against the copper plate 8. The handle portion 622 of the lever 62 is rotated upwardly to be perpendicular to the frame 63, and the driving portion 621 of the lever 62 is received in the driving hook 644 of the clip 64. The handle portion 622 of the lever 62 is rotated down toward the clip 64, and the driving hook 644 is driven downwardly until the clip 64 is in a final pressing position firmly pressing the copper plate 8 on the CPU 7. However, as best seen in FIG. 10, during rotation of the clip 64, the acting portions 641 may simultaneously move along the guiding grooves 65 toward the second walls 652. When this happens, the driving hook 644 moves beyond its correct position. As a result, when the handle portion 622 of the lever 62 is rotated, the driving portion 621 of the lever 62 cannot be accurately received in the driving hook 644 of the clip 64 to drive it. This leads to the clip 64 not reaching its correct final pressing position. Thus, the clip 64 fails to properly secure the copper plate 8 and the CPU 7 on the socket 61.
In view of the above, a new land grid array connector assembly that overcomes the above-mentioned disadvantages is desired.
Accordingly, an object of the present invention is to provide an electrical connector assembly such as a land grid array (LGA) connector assembly for electrically connecting an electronic package such as a central processing unit (CPU) with a circuit substrate such as a printed circuit board (PCB), whereby the LGA connector assembly has a fastening device for securely and reliably locating the CPU in the LGA connector assembly.
Another object of the present invention is to provide a fastening device for an electrical connector such as an LGA socket to securely and reliably locate an electronic package such as a CPU in the LGA socket.
To achieve the above-mentioned objects, an LGA connector assembly in accordance with a preferred embodiment of the present invention is for electrically connecting a CPU with a PCB. The LGA connector assembly comprises a socket and a fastening device surrounding the socket. The fastening device comprises an insulative frame having a first side and a second side opposite to the first side, a lever pivotably assembled to the first side of the frame, and a metal clip pivotably mounted to the second side of the frame.
The frame forms a pair of guiding grooves at opposite ends of the first side. Each guiding groove is bounded in part by a lower wall and an upper wall. The lever comprises a pair of acting portions movably received in the guiding grooves, a driving portion disposed between and offset from the acting portions, and a handle portion bent perpendicularly from a distal end of one of the acting portions. The clip forms a driving hook at a free end thereof. The clip is rotated down from a perpendicular open position to a horizontal closed position. Then, the handle portion of the lever is rotated upwardly from a horizontal open position to a perpendicular position. The acting portions of the lever are rotated about the corresponding lower arcuate walls, and the driving portion is received in the driving hook of the metal clip. Then the handle portion of the lever is rotated down toward the metal clip, and the acting portions of the lever are driven to slide to reach the corresponding upper arcuate wall. The lever is at a final horizontal closed position, with the driving portion pressing the driving hook of the metal clip downwardly.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: